KR102370624B1 - Wafer Processing Equipment With Exposed Sensing Layers - Google Patents

Abstract

Embodiments include devices and methods for detecting particles, monitoring etch or deposition rates, or controlling operation of a wafer fabrication process. In one embodiment, one or more micro sensors are mounted on the wafer processing equipment and can measure material deposition and removal rates in real time. The microsensors are selectively exposed so that the sensing layer of the microsensor is protected by a mask layer during active operation of the other microsensor, and when the other microsensor reaches end-of-life, the protective mask layer is removed to expose the sensing layer. can Other embodiments are also described and claimed.

Description

Wafer Processing Equipment With Exposed Sensing Layers

[0001] This application claims priority to U.S. Patent Application Serial No. 15/247,717, filed on August 25, 2016, the entire contents of which are hereby incorporated herein by reference.

[0002] Embodiments relate to the field of semiconductor processing, and more particularly to devices and methods for measuring material deposition or material removal in a wafer processing tool.

[0003] A major concern in the manufacture of semiconductor devices is particle contamination of semiconductor wafers. Such contamination typically occurs during one or more operations performed by a wafer processing tool during fabrication of semiconductor devices. For example, a wafer processing tool may include several chambers interconnected by several interfaces, eg load locks, of any of these system components. The actuation or operation may generate metallic or non-metallic particles such as aluminum, stainless steel, zirconium or other particles that may contaminate the semiconductor wafer within the tool. One of ordinary skill in the art will appreciate that particles may originate from many sources within a wafer processing tool other than interfaces and moving parts, so that the above is provided by way of example.

[0004] To ascertain a source and/or root cause of particle contamination, semiconductor wafers are periodically processed through one or more chambers of a wafer processing tool and then subjected to a particle inspection operation. The particle inspection operation may involve a processed wafer waiting for inspection by optical inspection equipment to ascertain the location and general size of the particles, followed by scanning electron microscopy, energy dissipation to determine the presence and/or composition of particles on the wafer. Requires waiting for inspection by spectroscopy or other inspection techniques. After detecting the presence and composition of particles, further troubleshooting may be necessary to ascertain which of the operations performed by the wafer processing tool actually caused particle contamination.

Fabrication of semiconductor devices may involve depositing and removing material, more particularly semiconductor material, on a substrate by a wafer processing tool using, for example, deposition or etching processes. can To accurately deposit or remove a specific amount of semiconductor material, film thickness measurement techniques may be used. For example, material deposition and material removal rates can be measured indirectly by using an ellipsometer to measure the amount of film deposited or removed after processing a wafer of semiconductor material for a given amount of time. In addition, sensors have been used to measure secondary factors that correlate with deposition/removal rates to indirectly estimate deposition/removal rates during the wafer fabrication process.

Embodiments have micro sensors, eg, sensors sized to MEMS-scale and/or manufactured using MEMS processes, to detect an amount or rate of material deposition or removal. wafer processing equipment. In one embodiment, the wafer processing equipment includes a particle monitoring device having micro sensors for detecting particles in the wafer processing tool, or a wafer processing tool having micro sensors for monitoring or controlling a wafer manufacturing process. do. Micro sensors of wafer processing equipment may include sensing layers and mask layers configured such that the sensing layers may be selectively protected or exposed. Thus, the sensing layer of a micro sensor may be protected by a mask layer while another micro sensor is exposed to actively detect particles and/or material deposition or removal. The mask layer may be removed to expose the sense layer when the other micro sensor has reached its end-of-life. As such, the micro sensors of the wafer processing equipment can be refreshed without interrupting the wafer fabrication process, for example without opening a chamber or process station of the wafer processing tool.

In one embodiment, a wafer processing equipment, eg, a wafer processing tool or a particle monitoring device, includes a first micro sensor and a second micro sensor. For example, the micro sensors may be mounted within a chamber volume of a process chamber of a wafer processing tool, or mounted on a support surface of a wafer substrate of a particle monitoring device. Each of the micro sensors may include a sensing layer covered by a mask layer. More specifically, the sensing layers may be protected by a mask layer during a step of the wafer fabrication process when different sensing layers of the same or different micro-sensor monitor the process. That is, the exposed sensing layer of the active micro sensor may be open to the surrounding environment and/or chamber volume to monitor the wafer fabrication process. The sensors may have respective parameters, eg, capacitance, and the parameters may change when material is removed from the sensor surfaces of the sensing layers. Accordingly, when material is removed from the exposed sensing layer, a corresponding change in parameter can be detected to sense amounts or rates of an etching process, eg, particle deposition or removal.

[0008] In one embodiment, the micro sensors include mask layers having different thicknesses. For example, a blanket mask layer may cover the sensing layers of several micro sensors, and the blanket mask layer may have a layer profile comprising a variable thickness. Thus, removal of the mask layer may allow the first sense layer to be exposed before the second sense layer, allowing the sense layers to be exposed independently and selectively to be sensed at different times in the wafer fabrication process.

[0009] In one embodiment, micro sensors include mask layers with different materials susceptible to etching by different etchants. That is, the first mask layer covering the first sensing layer may be different from the second mask layer covering the second sensing layer. For example, the first mask layer may include an oxide and the second mask layer may include a nitride. Thus, an etchant that attacks oxides can be used to remove the first mask layer and expose the first sense layer, and an etchant that attacks nitrides can be applied to remove the second mask layer and expose the second sense layer. there is. Thus, removal of the first mask layer may cause the first sense layer to be exposed at a different time than the second sense layer, such that the sense layers may be independently and selectively exposed to be sensed at different times in the wafer fabrication process. do.
Embodiments provide for initiating a wafer fabrication process in a process chamber having a chamber volume, wherein a first micro sensor and a second micro sensor are disposed within the process chamber, wherein a first sensing layer of the first micro sensor and a second micro sensor the second mask layer is exposed to the chamber volume; etching the first sensor surface on the first sensing layer of the first micro sensor with an etchant; and stripping the second mask layer of the second micro sensor to expose a second sensor surface on the second sensing layer of the second micro sensor to the chamber volume. In one embodiment, a third micro sensor is disposed within the process chamber, a third mask layer of the third micro sensor is exposed to the chamber volume, and the third mask layer may be thicker than the second mask layer.

[0010] The above summary does not include an exhaustive list of all aspects. It is contemplated to include all systems and methods that may be practiced from those disclosed in the detailed description that follows and particularly pointed out in the claims in conjunction with the present application, as well as all suitable combinations of the various aspects summarized above. . Such combinations have certain advantages not specifically described in the above summary.

1 is a diagram of a wafer processing system according to one embodiment;
2 is a diagram of a particle monitoring device according to an embodiment;
3 is a cross-sectional view of a particle monitoring device according to an embodiment.
4 is a cross-sectional view of several micro sensors mounted on a wafer processing tool, according to one embodiment.
5 is a diagram of a block diagram of an electronic circuit of a particle monitoring device or wafer processing tool, according to one embodiment.
6 is a cross-sectional view of several micro sensors having stacked structures including selectively exposable sensing layers, according to one embodiment.
7 is a cross-sectional view of several micro sensors with a blanket mask layer over selectively exposable sensing layers, according to one embodiment.
8 is a cross-sectional view of several micro sensors with mask layers of different materials over selectively exposable sensing layers, according to one embodiment.
9 is a perspective view of a micro sensor of a wafer processing system according to an embodiment.
10 is a perspective view of a micro sensor of a wafer processing system according to an embodiment.
FIG. 11 is a cross-sectional view taken along line AA of FIG. 10 of a micro sensor of a wafer processing system according to one embodiment;
12 is a schematic diagram of a micro sensor of the transistor sensor type of a wafer processing system, according to one embodiment.
13 is a schematic diagram of a micro-resonator type micro sensor of a wafer processing system, according to one embodiment.
14 is a schematic diagram of a micro sensor of the optical sensor type of a wafer processing system according to one embodiment;
15 is a diagram of a flow diagram illustrating operations of a method of refreshing micro sensors of a wafer processing equipment, according to one embodiment.
16A-16C are cross-sectional views illustrating operations of a method of refreshing micro sensors of a wafer processing equipment, according to an embodiment.
17 is a diagram of a flow diagram illustrating operations of a method of refreshing micro sensors of a wafer processing equipment, according to one embodiment.
18A-18F are cross-sectional views illustrating operations of a method of refreshing micro sensors of a wafer processing equipment, according to an embodiment.
19 is a block diagram of an exemplary computer system of a wafer processing system, according to one embodiment.

[0030] Devices and methods used for particle detection, etch/deposition rate monitoring, or other fabrication or control of a wafer fabrication process are described in accordance with various embodiments. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent to one skilled in the art that the embodiments may be practiced without these specific details. In other instances, well-known aspects have not been described in detail in order not to unnecessarily obscure the embodiments. Also, it should be understood that the various embodiments shown in the accompanying drawings are illustrative representations and are not necessarily drawn to scale.

[0031] Existing techniques for measuring material deposition and removal do not provide real-time measurement and control of the wafer fabrication process, or material deposition/removal based on correlation with a second factor rather than directly measuring deposition/removal. provides an estimate of For example, an ellipsometer can be used to measure film thickness, but since the ellipsometer is a periodic monitor, the ellipsometer can detect real-time excursions or drifts in deposition/removal rate over normal production runs. Drifts cannot be detected. Also, sensors installed in the process chamber of a wafer processing tool for measuring secondary factors such as RF matching positions or gas concentrations of the plasma do not directly measure the variable of interest (deposition/removal rates), and such measurements do not This becomes more difficult in chambers that do not have

[0032] Wafer processing equipment with micro sensors for measuring material deposition or material removal in all pressure regimes, eg under vacuum conditions, and under plasma-less conditions It is described below. For example, a micro sensor mounted on a process chamber may include a sensor surface, and a parameter of the micro sensor, eg, capacitance, may change as material is deposited on or removed from the sensor surface. Accordingly, real-time measurements of material deposition or removal quantities or rates, as well as uniformity of such quantities or rates, can be monitored and used to control the wafer fabrication process performed by the wafer processing system.

[0033] Microsensors used for real-time measurements of wafer fabrication processes will change over time. More specifically, by design, the sensor surface can be removed by etching (or grown by deposition) and roughened, the surface area of the sensor surface can be changed, the sensor surface can be oxidized, and so on. . These changes may affect the sensitivity of the micro-sensor and reduce the reliability of the micro-sensor. For example, the micro sensor may lose reliability after tens of wafer processing cycles, requiring the process chamber to be opened to clean or replace the micro sensor. However, refreshing such microsensors can disrupt the process flow of the wafer fabrication process, and thus the need to extend the sensing capability of wafer processing equipment when microsensors deteriorate without stopping the wafer fabrication process. There is this.

In an aspect, wafer processing equipment may include selectively exposable micro sensors to allow a different micro sensor to replace a degraded micro sensor. For example, each micro sensor may include several layers of sensing layers separated by intervening mask layers. Accordingly, after the first sense layer is degraded, the sense layer and one or more intervening mask layers may be removed to expose the underlying sense layer for active operation. Alternatively, several laterally separated sensing layers may be covered by a blanket mask layer having a variable thickness. Accordingly, the blanket mask layer may be etched to sequentially expose the sensing layers based on the thickness of the blanket mask layer overlying the respective sensing layers. For example, as the blanket mask layer is removed, a first sensing layer below a first thickness of material may be exposed, and then after some time a second sensing layer below a second thickness of material greater than the first thickness is exposed. can be The use of sensor approaches that allow selective exposure of new sensing layers to replace degraded sensing layers will increase the lifetime of wafer processing equipment and, more specifically, the need to open the process chamber for sensor maintenance. The number of wafer processing cycles of a previously achievable wafer fabrication process may be increased.

It will be appreciated that the wafer processing systems and methods described below may be used in any form factor or process in which materials are deposited on or removed from a substrate. More specifically, while wafer processing systems and methods are described in the context of wafer processing for the manufacture of integrated circuits, the devices and methods are also described in the context of displays in the electronics industry and/or photovoltaic cells in the solar industry. It may be adapted for use in other technologies.

1 , there is shown a diagram of a wafer processing system according to one embodiment. The wafer processing system 100 may include a wafer processing tool 102 communicatively coupled to a computer system 104 by a communication link 106 . The communication link 106 may be a wired or wireless connection, ie, the wafer processing tool 102 may communicate with the computer system 104 directly or wirelessly. Data may be communicated by communication link 106 from wafer processing tool 102 and/or devices within wafer processing tool 102 , although in some embodiments, devices within wafer processing tool 102 are passive devices. device) may be understood. That is, the device may be processed by the wafer processing tool 102 and may undergo a change, which may be measured after the device is removed from the wafer processing tool 102 . This may be a feature of, for example, a particle detection tool or an etch/deposition monitoring tool, as described below.

The wafer processing tool 102 may include a buffer chamber 108 physically coupled to the factory interface 110 by one or more loadlocks 112 . Also, one or more process chambers 114 may be physically coupled to the buffer chamber 108 by one or more respective loadlocks 112 . The buffer chamber 108 may act as an intermediate volume greater than the respective volumes of the process chambers 114 , maintained at a low pressure, albeit at a pressure higher than the process pressures within the process chambers 114 . Accordingly, a semiconductor wafer, eg, a silicon wafer, may be moved between chambers of the wafer processing tool 102 under vacuum conditions during fabrication of semiconductor devices. Such movement may be facilitated by various devices included within the wafer processing tool 102 , such as robots, robotic arms, shuttles, and the like.

Various manufacturing operations may be performed in the process chambers 114 . For example, the at least one process chamber 114 may be an etch chamber, a deposition chamber, a chamber of a semiconductor lithography tool, or any other semiconductor process chamber. As such, the process chamber 114 may be used to perform a wafer fabrication process under vacuum conditions, atmospheric conditions, or any other pressure regime.

[0039] In addition to various pressure regimes, process chambers 114 may also be used to perform manufacturing processes having different energy states. For example, the process chamber 114 may be a radical-driven etch chamber or deposition chamber that does not contain a plasma. That is, the process chamber 114 may be free of plasma during the wafer fabrication process. Alternatively, the process chamber 114 may be a plasma-based etching or deposition chamber.

During a wafer fabrication process, a semiconductor wafer may be transferred from the buffer chamber 108 into one of the process chambers 114 via a loadlock 112 . The process chambers 114 may have the chamber pressure lowered to a vacuum using, for example, a vacuum pump and/or a turbo pump ( FIG. 4 ). In the context of this description, a vacuum can be any pressure less than 0.5 atm. In one embodiment, a vacuum within the process chamber 114 exists when the process chamber 114 has a chamber pressure that is less than the pressure of the buffer chamber 108 , for example less than 100 millitorr. Accordingly, the manufacturing operation performed in the process chamber 114 may be performed under vacuum conditions.

One or more particles may be generated during a manufacturing operation performed in the process chamber 114 . For example, the particles may become active when a certain action occurs, for example when the valve of the load lock 112 is opened, when the load lock door is locked, when the lift pins move. , or any other tool operation, may be metallic or non-metallic particles that are released into the process chamber 114 when they occur. The ejected particles may settle on the semiconductor wafer, and the location and time of deposition of the particles may correspond to the source of particle contamination. For example, particles may land on a semiconductor wafer closer to the loadlock 112 and at the time the loadlock 112 is closed, which may cause components of the loadlock 112 and/or the loadlock ( 112) may indicate that the operation is a source of particles. Thus, it can be seen that particle monitoring, which provides information about where and when particles settle on a semiconductor wafer, can be useful in determining the source of particle contamination.

Referring to FIG. 2 , there is shown a diagram of a particle monitoring device according to one embodiment. The particle monitoring device 200 may be configured to be moved between chambers of the wafer processing tool 102 , for example, the buffer chamber 108 and/or the process chambers 114 . For example, the particle monitoring device 200 may include a wafer substrate 202 having the same overall form factor and/or material and shape as a semiconductor wafer. That is, the wafer substrate 202 may be at least partially composed of a semiconductor material, for example, a crystalline silicon material. Further, the wafer substrate 202 may have an essentially disk-shaped wafer form factor and includes a support surface 204 having a diameter 206 . The support surface 204 may be the upper surface of the disk, and the lower surface (not shown) of the wafer substrate 202 may be spaced from the support surface 204 by a thickness 208 . In one embodiment, the wafer form factor of the wafer substrate 202 includes a diameter 206 between 95 and 455 mm, for example, the diameter 206 may be nominally 100 mm, 300 mm or 450 mm. Further, the wafer form factor of the wafer substrate 202 may include a thickness 208 of less than 1 mm, for example 525 μm, 775 μm, or 925 μm. The thickness 208 may also be greater than 1 mm, for example a few millimeters to 10 mm. Accordingly, the particle monitoring device 200 may be fabricated using readily available wafer materials and typical wafer fabrication processes and equipment, and will essentially simulate a semiconductor wafer when processed by the wafer processing tool 102 . can

The particle monitoring device 200 may include several micro sensors mounted on the support surface 204 at predetermined locations. The micro sensors may be one or more of the micro sensor types described below. For example, the micro sensors 210 may include respective sensing layers covered by corresponding mask layers. The micro sensors 210 may include respective parameters and may include respective sensor surfaces on respective sensing layers. Accordingly, respective parameters may change as material is deposited on or removed from respective sensor surfaces. A number of micro sensors 210 may be mounted on the support surface 204 , for example thousands to millions of micro sensors. Each micro sensor 210 may have a known location. For example, the first micro-sensor 212 may be located at a first position, and the second micro-sensor 214 may be located at a second position. The second location may have a known position relative to the first location or to some other reference point on the particle monitoring device 200 .

The micro sensors 210 may be randomly distributed over the support surface 204 , or may be arranged in a predetermined pattern. For example, the micro sensors 210 shown in FIG. 2 appear to be randomly distributed over the support surface 204 , although their absolute or relative positions may be predetermined and known. In one embodiment, the micro sensors 210 are arranged in a predetermined pattern, eg, a grid pattern, concentric circle pattern, spiral pattern, or the like. Such patterns may be achieved using known etching processes to form the micro sensors 210 at precise locations on the support surface 204 of the particle monitoring device 200 .

In one embodiment, the micro sensors 210 are spread over a majority of the surface area of the support surface 204 . For example, an outer profile drawn through the outermost micro sensors 210 of a micro sensor array may depict an array area that is at least half the surface area of the support surface 204 . In one embodiment, the array area is at least 75% of the surface area of the support surface 204 , eg, greater than 90% of the surface area.

The micro sensors 210 of the particle monitoring device 200 may be interconnected with each other or other circuitry via one or more electrical connectors. For example, the micro sensors 210 may be connected in series by an electrical trace 216 extending over the support surface 204 . Alternatively or additionally, several micro sensors 210 may be electrically connected in parallel by respective electrical traces 216 . Accordingly, electrical connections may be made between the micro sensors 210 , or the micro sensors 210 may use electrical traces, electrical leads, vias, and other known types of electrical connectors. Thus, it can be connected to the wafer electronics, that is, the electronic circuit 218 .

Each micro sensor 210 of the particle monitoring device 200 may be configured to detect a change in a given parameter when the particle interacts with the sensor. For example, the micro sensor 210 may include a capacitive micro sensor as described below, which changes when material is deposited on or removed from the sensor surface of the micro sensor 210 . It can have a capacitance of Accordingly, the capacitance may change when the micro sensor 210 receives particles within a chamber of the wafer processing tool 102 , for example, the process chamber 114 . Here, the term “accommodates” refers to the interaction between the particle and the micro sensor 210 that affects the capacitance. It will be appreciated that the particle monitoring device 200 may include other micro sensor types as described below, such that other parameters may be sensed when a particle is received by such micro sensors. For example, a parameter may be a voltage, current, or other physical or other physical or It may be an electrical characteristic. Other particle-sensor interactions will be understood by one of ordinary skill in the art upon reading this description.

Referring to FIG. 3 , there is shown a cross-sectional view of a particle monitoring device according to one embodiment. The micro sensors 210 may be packaged on a wafer substrate 202 that may be automatically loaded into and moved throughout the system, similar to the loading and processing of a typical semiconductor wafer. Accordingly, the micro sensors 210 may experience the same environment as a production semiconductor wafer. In one embodiment, a sensor layer 302 with several micro sensors 210 covers at least a portion of the wafer substrate 202 . Accordingly, the micro sensors 210 of the sensor layer 302 are mounted on the support surface 204 of the wafer substrate 202 .

[0049] The sensor layer 302 should not be confused with a sensing layer, as described below. More specifically, the sensor layer 302 may be a layer of wafer processing equipment on which one or more micro sensors 210 are disposed, while the sensing layer is configured to detect etch/deposition rate, gas concentration, by-product build-up, particles, etc. It may be one of several layers of an individual micro-sensor 210 that may be exposed to the surrounding environment.

Any portions of the particle monitoring device 200 may be formed from a stack of standard silicon on insulator (SOI) substrates or other types of wafers. Wafers may be bonded at the wafer level, ie by bonding individual wafers with integrally formed functional components. Alternatively, the wafers may have individual modules, eg, chips, sensors, etc., bonded before or after forming the particle monitoring device 200 . It will be appreciated that such processes may allow the use of SOI technology to optimize etch sensors, high temperature electronics, or other modules/components to be integrated into the particle monitoring device 200 . It will be appreciated that such processes may also be used to fabricate portions of wafer processing equipment described below, such as micro sensors 210 of wafer fabrication processing equipment.

In one embodiment, the wafer substrate 202 is configured to protect the electronic circuitry 218 of the particle monitoring device 200 from attack by a plasma within the wafer processing tool 102 . As such, wafer substrate 202 may include electronic circuitry 218 interposed between top layer 306 and bottom layer 308 , eg, wafer electronics. For example, the electronic circuit 218 may include a power source 304 , such as a thin-film battery. The thin film battery may be encapsulated between the layers 306 , 308 of silicon, thus being protected against plasma attack from the top or bottom by the two silicon wafers. Additionally, the power source 304 may be protected against plasma attack from the sides by a barrier seal 310 . A barrier seal 310 may be interposed between the top layer 306 and the bottom layer 308 around the power source 304 . More specifically, the barrier seal 310 may extend around a circumference of the wafer substrate 202 to form a protective wall surrounding the sides of the power source 304 . Accordingly, the power source 304 may be encapsulated within the wafer substrate 202 .

The power source 304 may be electrically coupled to one or more components of the electronic circuitry 218 in the top layer 306 and/or the sensor layer 302 . For example, electronic circuitry 218 , eg, control electronics, such as a processor, memory, or communication electronics, may be embedded in the top layer 306 of the wafer substrate 202 . The power source 304 may be connected to the electronic circuitry 218 in the top layer 306 by electrical connections such as through silicon vias extending through one or more layers of the particle monitoring device 200 . . Similarly, the power source 304 and/or the electronic circuitry 218 in the top layer 306 , eg, a processor, electrically connects the micro sensors 210 in the sensor layer 302 by electrical traces or electrical vias. can be connected to Accordingly, the power source 304 may be electrically coupled to the processor, micro sensors 210 or other electronic circuitry 218 of the electronic circuitry 218 to power the electronic device.

The physical, chemical and electrical protection of the wafer processing tool 200 and/or some areas of the wafer processing equipment caps the components after bonding the electronic circuitry 218 onto the wafer substrates at the module or chip level. capping) may be provided. For example, after batteries, processors, sensors, wireless communication modules, etc. are bonded, they may be capped, for example, by a barrier layer 312 . However, some components may be exposed to the wafer processing environment. For example, micro sensors 210 may be exposed on wafer processing tool 200 or wafer processing equipment to monitor etching and deposition processes, as described below.

The micro sensors 210 may be exposed to plasma within the wafer processing tool 102 , such that the sensors may eventually wear out. Sensor methods for extending the overall lifetime of the sensor will be described below. Nevertheless, it may be advantageous to package the micro sensors 210 so that they are recyclable. In one embodiment, the packaging of the micro sensors 210 includes a barrier layer 312 between the micro sensor 210 and an underlying substrate. For example, in the case of particle monitoring device 200 , barrier layer 312 may be disposed between micro sensor 210 and support surface 204 of wafer substrate 202 . The micro sensor 210 may be electrically connected to the wafer electronics, ie, the electronic circuitry 218 , via the barrier layer 312 using known interconnection techniques, such as through-silicon vias. A barrier layer 312 between the control electronics and the sensors may protect the electronics during recycling. For example, the micro sensor 210 may be removable by stripping agents, ie, a plasma, gas or liquid etchant, and the barrier layer 312 may not be strippable by the same stripping agent. That is, barrier layer 312 can be any conductive or insulating material that is impermeable to a stripper, such as a gaseous or liquid etchant. Thus, when the microsensors 210 have reached the end of their useful life, the plasma can dislodge the microsensors of the sensor layer 302 as a barrier layer without degrading the electronic circuitry 218 embedded in the wafer substrate 202 . may be applied to peel from 312 . Similarly, mechanical peeling can be used to remove worn sensors. Next, a new sensor layer 302 with a new set of micro sensors 210 is applied as a barrier layer ( 312) may be formed.

The components of the particle monitoring device 200 may be formed using known semiconductor processes and techniques. For example, as described above, electrical connections between sensors and electronic circuitry 218 may be formed through barrier layer 312 and/or wafer substrate 202 using through-silicon vias. Further, components may be embedded in the layers of the particle monitoring device 200 using known techniques. For example, microsensors 210 may be individually formed and then mounted onto barrier layer 312 using flip chip technology during a recycling process.

The implementation of the micro sensor 210 in the particle monitoring device 200 represents an embodiment using the micro sensors 210 for particle detection. There are other uses of micro sensors 210 in wafer fabrication processing equipment and methods. For example, micro sensors 210 may be mounted on the wafer processing tool 102 to detect or measure an etch/deposition rate, such data being capable of controlling a wafer fabrication process, eg, an etching or deposition process. can be used to

Referring to FIG. 4 , there is shown a cross-sectional view of several micro sensors mounted on a wafer processing tool, according to one embodiment. A wafer 402 , for example a wafer of semiconductor material or a wafer substrate 202 of the particle monitoring device 200 , may be subjected to a wafer fabrication process in a process chamber 114 of a wafer processing tool 102 . As the wafer 402 moves through the wafer processing tool 102 , the wafer 402 may experience different pressure conditions. For example, the semiconductor wafer 402 may be inserted into the factory interface 110 in standby conditions. Next, as the semiconductor wafer 402 enters the loadlock 112 between the factory interface 110 and the buffer chamber 108 , the loadlock 112 may be brought to a vacuum of 120 milliTorr. The semiconductor wafer 402 may then be passed from the loadlock 112 into the buffer chamber 108, where the pressure of the buffer chamber 108 is 100 milliTorr.

The wafer 402 may be transferred from the buffer chamber 108 to one of the process chambers 114 via the loadlock 112 . For example, the process chamber 114 may include a chamber wall 404 around a chamber volume 406 , the chamber volume 406 may be sized to receive a wafer 402 . Accordingly, semiconductor material may be deposited on or removed from the wafer 402 during a wafer fabrication process within the process chamber 114 . During the wafer fabrication process, the chamber volume 406 of the process chamber 114 may have the chamber pressure lowered to a vacuum using a vacuum source 408 such as, for example, a vacuum pump and/or a turbo pump. In the context of this description, a vacuum can be any pressure less than 0.5 atm. In one embodiment, a vacuum within the process chamber 114 exists when the process chamber 114 has a chamber pressure that is less than the pressure of the buffer chamber 108 , for example less than 100 milliTorr. Accordingly, the process chamber 114 may be under vacuum conditions during a fabrication operation of a wafer fabrication process. Further, vacuum conditions may reduce or remove gas mixtures from the chamber volume 406 , such that the chamber volume 406 may be free of plasma during the wafer fabrication process.

One or more micro sensors, for example micro sensors 210 , may be mounted to the wafer processing tool 102 . The micro sensors may be one or more of the micro sensor types described below. For example, the micro sensors 210 may include respective sensing layers covered by corresponding mask layers. The micro sensors 210 may be mounted at one or more locations on the process chamber 114 within the chamber volume 406 . More specifically, several micro sensors 210 may be mounted at predetermined locations on the chamber wall 404 within the chamber volume 406 .

In one embodiment, the micro sensor(s) 210 are mounted on portions of the wafer processing tool 102 other than the chamber wall 404 . For example, instead of, or in addition to, the micro sensors 210 being mounted on the chamber wall 404 , one or more micro sensors 210 may be mounted on a wafer holder within the process chamber 114 ( 410). The wafer holder 410 may be, for example, an electrostatic chuck with electrode(s) for electrostatically clamping the wafer 402 during a wafer fabrication process. The wafer holder 410 may include a holding surface 412 to which the wafer 402 is clamped. For example, the holding surface 412 may be a layer of dielectric material over the wafer holder 410 , and the micro sensor 210 may be mounted on the holding surface 412 . More specifically, the micro sensors 210 may be mounted on the holding surface 412 in an area proximate to the wafer 402 and/or laterally offset from the wafer 402 during the wafer fabrication process. For example, a process kit may include a ring around a wafer 402 on a holding surface 412 , and a micro sensor 210 may be mounted on the process kit.

Micro sensors 210 are located in, or in the process chamber 114 of, sufficiently proximate to the wafer 402 to detect changes in material deposition or removal rates of the wafer 402 . It is contemplated that it may be embedded in consumable or non-consumable parts, for example wafer holder 410 . For example, the wafer 402 may have a forward facing surface, ie, a surface facing away from the holding surface 412 towards the plasma, and the micro sensor 210 may have a sensor surface that is sensitive to material deposition/removal also facing forward. may be mounted on the holding surface 412 to

It will be appreciated that the micro sensors 210 may be mounted at locations on the wafer processing tool 102 other than locations within the process chamber 114 . For example, one or more micro sensors may be mounted on, in, or proximate to the loadlock 112 . Similarly, the micro sensor 210 controls the flow of a gas line (not shown) of the wafer processing tool 102 to a vacuum source 408 , to name a few exemplary locations. It may be mounted on, in, or proximate to the pressure control valve 414 of 102 , the robot of the wafer processing tool 102 , or the lift pins of the wafer processing tool 102 . The micro sensors 210 may be mounted proximate to other locations of the wafer processing tool 102 depending on the particular process measurement and control desired. Although "proximally" is used herein as a relative term, the presence of the micro sensor 210 near a particular component of the wafer processing tool 102 is the presence of material or particles deposited on or removed from the component. It will be understood that it is intended to describe a distance that makes it possible to statistically interact with the sensor. Examples of such interactions are further described in connection with the methods described below.

[0063] As used herein, the term “micro” may refer to the descriptive size of certain sensors or structures in accordance with embodiments. For example, the term “micro sensor” may refer to a capacitive sensor having dimensions on the scale of a few nanometers to 100 μm. That is, in one embodiment, micro sensors 210 as described below may have typical dimensions in the range of 0.05 to 100 μm for individual cells that may be connected in parallel or series. Accordingly, microsensors 210 as described herein are readily distinguishable from other sensor types, such as microbalances, which are instruments capable of accurate weight measurements on the order of parts per million of a gram. That is, microbalances can measure weight on a micro scale, but are not within the same size range as the micro sensors described herein. The difference in size range is advantageous because at least a few micro-sensors, eg, thousands, can be fitted elsewhere on the chamber volume 406 or wafer processing tool 102 , while a few microbalances can fit into the semiconductor wafer 402 . ) cannot fit into a chamber volume 406 sized to receive it.

[0064] As used herein, the term “micro sensors” may also refer to sensors fabricated using materials and manufacturing processes associated with microelectromechanical systems (MEMS). That is, the micro sensors 210 described herein may be fabricated using MEMS processes such as deposition processes, patterning, etching, and the like. Accordingly, the micro sensors 210 may be MEMS-scale sensors having a size and structure formed using MEMS processes. It should be understood, however, that the embodiments are not necessarily limited thereto, and certain aspects of the embodiments may be applicable to larger and possibly smaller size scales.

Although only one micro sensor may be mounted on the wafer processing tool 102 , multiple micro sensors, such as hundreds to millions of micro sensors, may be fitted into the chamber volume 406 , or 102) may be mounted elsewhere. That is, given the MEMS-scale sized micro-sensors described below, many micro-sensors are located along the wafer processing tool 102 , for example the chamber wall 404 (or other components of the wafer processing tool 102 ). Distributed around can monitor wafer fabrication process parameters, eg, deposition/removal of semiconductor material within process chamber 114 in real time.

Each micro sensor 210 may have a known location. For example, the first micro sensor may be located at a first predetermined location on the wafer processing tool 102 , eg, a first location within the chamber volume 406 , and the second micro sensor may be located at the wafer processing tool 102 . ) on a second predetermined location, for example a second location within the chamber volume 406 . The micro sensors 210 may be distributed randomly or in a predetermined pattern on the process chamber 114 . For example, the second location may have a known position relative to the first location, or some other fiducial point on the process chamber 114 . Accordingly, the uniformity of material deposition/removal can be determined as described below by comparing real-time measurements from the first micro sensor and the second micro sensor.

The wafer processing tool 102 may include other sensors and/or measurement instruments for detecting a process parameter of a wafer manufacturing process. Other sensors and/or measurement instruments may not be micro sensors. For example, in contrast to MEMS-scale sensors described below, the wafer processing tool 102 is configured to detect an optical emissions spectrometry (OES) signature of the chamber volume 406 during a wafer fabrication process. may include an optical spectrometer 416 mounted on or otherwise mounted on the process chamber 114 . The OES signature may identify the type and amount of elements in the chamber volume 406 . For example, the OES signature can identify which chemical elements are present in the plasma within the chamber volume 406 during the wafer fabrication process. Other sensors may be used to detect other process parameters of the wafer fabrication process performed in chamber volume 406 . Such other sensors may include electrical sensors for measuring electrical power delivered to the process chamber 114 or wafer 402 , electrical sensors for measuring electrical characteristics of the wafer holder 410 , and the like. Such sensors cannot measure the actual amount or rate of deposition/removal of semiconductor material 1108 , but may nevertheless be correlated with actual deposition/removal measurements obtained by micro sensors 210 for reasons described below. can

Other sensors may also be used to gather information correlating with the presence of particles within the wafer processing tool 102 . For example, one or more measurement devices, such as accelerometers (not shown), may be mounted on moving parts of the wafer processing tool 102 . In one embodiment, the robot or robot arm includes an accelerometer for sensing motion of the robot. Alternatively, the load lock door includes an accelerometer. Thus, process parameters of the wafer fabrication process, e.g., motion data indicative of robot movement, can be detected by an accelerometer and correlated with particle sensing data collected from the micro-sensor 210 to determine the source of the particulate. . Applications of such other sensors, for example accelerometers, are further described below.

The micro sensors 210 and/or measurement instruments or devices of the wafer processing tool 102 may be interconnected with each other or other circuitry via one or more electrical connectors. For example, the micro sensors 210 may be connected in series by electrical traces extending over the chamber wall 404 and/or wafer holder 410 . Alternatively or additionally, several micro sensors 210 may be electrically connected in parallel by respective electrical traces 216 . Accordingly, electrical connections may be made between the micro sensors 210 and/or the micro sensors 210 may use electrical traces, electrical leads, vias, and other known types of electrical connectors to make electronic circuits ( 218) can be connected.

[0070] Referring to FIG. 5, there is shown a diagram of a block diagram of an electronic circuit of a particle monitoring device or wafer processing tool, according to one embodiment. The electronic circuitry 218 of the particle monitoring device 200 or wafer processing tool 102 may be supported by a wafer 402 or an underlying structure of the wafer processing tool 102 . For example, the electronic circuitry 218 may be mounted on the top layer 306 of the particle monitoring device 200 as described above. Electronic circuitry 218 may be encapsulated within the housing. The housing and/or electronic components of the electronic circuitry 218 may be integral with the wafer 402 , for example the housing may be layers of a wafer substrate encapsulating the electronic circuitry 218 . Alternatively, the housing may be mounted on the wafer processing tool 102 , for example on a chamber wall 404 or wafer holder 410 . Similarly, the housing may be mounted on another portion of the wafer processing tool 102 , such as on an exterior surface outside the chamber volume 406 . Accordingly, the electronic circuitry 218 may be co-located with respect to the micro-sensor 210 or may be located remotely. Nevertheless, the electronic circuitry 218, even when mounted remotely to the microsensor 210 , can be connected to one or more input/output (I/O) connections 502 , such as electrical traces, electrical leads or vias. It may be in an electrical connection state with the micro sensor 210 through .

Electronic circuitry 218 of the wafer processing equipment may include a clock 504 . The clock 504 may be an electronic circuit having an electronic oscillator, eg, a quartz crystal, to output an electrical signal having an accurate frequency, as is known in the art. Accordingly, the clock 504 may be configured to output a time value corresponding to an electrical signal received via the I/O connection 502 . The time value may be an absolute time value independent of other operations, or the time value may be synchronized with other clocks within the wafer processing equipment. For example, the clock 504 may be synchronized with a system clock of the wafer processing tool 102 or a system clock of a host computer of a manufacturing facility linked to the wafer processing tool 102 , such that the clock 504 . The time value output by n corresponds to a system time value and/or system operations output or controlled by the system clock. Clock 504 may be configured to initiate the output of a time value when a particular process operation occurs. The electronic circuitry 218 of the wafer processing equipment may include a network interface device 506 for transmitting and receiving communications between the wafer processing tool 102 and a host computer.

Electronic circuitry 218 of the wafer processing equipment may include a processor 508 . The processor 508 may be, for example, electrically coupled to a clock 504 by a bus 510 and/or traces. Processor 508 represents one or more general-purpose processing devices, such as a microprocessor, central processing unit, and the like. More specifically, the processor 508 is a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or instructions It may be processors that implement a combination of sets. The processor 508 may also include one or more such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), a network processor, and the like. They may be special purpose processing devices.

The processor 508 is configured to execute processing logic to perform the operations described herein. For example, the processor 508 may be configured to receive and analyze input signals from the particle monitoring device 200 or several micro sensors 210 located at different predetermined locations on the wafer processing tool 102 . can Accordingly, the processor 508 may determine and record data related to the micro sensors 210 to which it is operatively connected. For example, the processor 508 may record the position of the micro sensor 210 when the capacitance of the micro sensor 210 changes. The processor 508 may also receive time value outputs from the clock 504 corresponding to each received input signal, and write the time value outputs to memory as a time stamp. Accordingly, the processor 508 may compare the input signals from several micro sensors 210, for example, to determine the uniformity of the wafer fabrication process at a given time. The processor 508 may be configured to determine other types of information based on signals received from the micro sensors 210 . For example, input signals received from one or more micro sensors 210 may be used to determine an endpoint of a wafer fabrication process or a root cause of a change in a wafer fabrication process, as described below.

Other functionality may be provided by the processor 508 as described herein. For example, the processor 508 may include a signal processing function, eg, may convert an analog signal from the micro sensor 210 to a digital signal. Of course, a dedicated digital-to-analog converter may also be used for such purposes. Similarly, any of the processing functions described, such as filtering displacement currents, performing operations making logical decisions on data such as referencing lookup tables, applying correction factors, Other electronic devices may be used, for example. Further, it will be understood that such processing may be performed in a local manner or in a distributed manner, as is known. Accordingly, such electronics and processing techniques are not discussed in detail herein for the sake of brevity.

Monitoring of the micro sensors 210 may be performed by the processor 508 individually or in groups. That is, the processor 508 may monitor and record individual data for each micro-sensor 210 . Thus, each micro sensor 210 may be individually identifiable, for example, by a unique sensor identification number associated with a location or other sensor-specific data. In one embodiment, micro sensors 210 may be monitored in groups. For example, the processor 508 may monitor and record bank data for a group of one or more micro sensors 210 . These groups may be referred to as sensor blocks, and each sensor block may have a corresponding power source and processor. That is, the sensor blocks can function independently of each other and can be individually monitored or controlled. Thus, a group of micro sensors 210 may be associated with a location or other group-specific data corresponding to the group of sensors as a whole.

The electronic circuitry 218 of the wafer processing equipment may include, for example, a memory 512 mounted on a wafer substrate 202 or a chamber wall 404 . Memory 512 includes main memory (eg, read-only memory (ROM), flash memory, dynamic random access memory (DRAM), such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.); may include one or more of static memory (eg, flash memory, static random access memory (SRAM), etc.), or secondary memory (eg, a data storage device). The processor 508 may communicate with the memory 512 via a bus 510 or other electrical connection. Accordingly, the processor 508 is operatively coupled to the memory 512 to write to the memory 512 a predetermined position of the triggered micro-sensor 210 and a time value output by the clock 504 . can do. That is, the memory 512 determines the time when a particle or material is deposited on or removed from the micro-sensor 210 , and the time when the material settles on the micro-sensor 210 or is removed from the micro-sensor 210 . It is possible to record where the affected micro-sensor is mounted when descending from it.

The electronic circuitry 218 of the wafer processing tool 102 may include a power source 304 as described above. Power supply 304 may include a battery, capacitor bank, or other known power supply device. Power supply 304 is electrically coupled via bus 510 to one or more of the components of electronic circuitry 218 , such as micro sensors 210 , clock 504 , processor 508 , or memory 512 . It can be connected to and can supply power.

The electronic circuitry 218 of the wafer processing tool 102 may include additional components. For example, the electronic circuitry 218 may be configured to output a time value when the particle monitoring device 200 stops moving, eg, after being loaded into a particular process chamber 114 of the wafer processing tool 102 . may include an accelerometer 514 that triggers a clock 504 to start. Accordingly, the time value may provide information regarding when the particle monitoring device 200 is loaded into a particular processing station of the wafer processing tool 102 . The electronic circuitry 218 may include a frequency source 516 , such as a wide frequency source 516 , or a detector 518 . Frequency source 516 and detector 518 may have particular applications in connection with particular embodiments of micro sensors 210 of wafer processing tool 102 . For example, frequency source 516 and detector 518 may be used to drive and monitor micro-sensors of the micro-resonator type, as described below.

The components of the electronic circuit 218 described above are illustrative and not limiting of the range of sensors that may be used. For example, additional sensors, such as a temperature sensor 520 , may be incorporated into the fabrication of the wafer processing tool 102 . The temperature sensor 520 may monitor the temperature of one or more components of the wafer processing tool 102 , eg, the chamber volume 406 . Various embodiments of micro sensors 210 are now described. Initially, it is noted that the configurations and examples of micro sensors 210 are exemplary in nature, and that many additional configurations are contemplated by those skilled in the art based on this description.

[0080] Referring to FIG. 6, there is shown a cross-sectional view of several micro sensors having laminate structures comprising selectively exposable sensing layers, according to one embodiment. Several micro-sensors 210 of the type described below may be disposed within the process chamber, for example, capacitive quartz crystal micro-balance (QCM) or micro-resonator sensors. For example, the first micro sensor 212 and the second micro sensor 214 may be mounted on a wafer substrate 202 or a mounting surface 602 of the process chamber 114 . The first micro-sensor 212 and the second micro-sensor 214 can be adjacent to each other, for example in a side-by-side configuration, each micro-sensor comprising one or more sensing layers 604 and one or more mask layers 606 . may include Further, the sense layers 604 of the first micro sensor 212 and the second micro sensor 214 are formed when the sense layer 604 of the second micro sensor 214 is masked by the mask layer 606 , The sensing layer 604 of the first micro sensor 212 may be selectively exposable such that it is exposed to the ambient environment, eg, the chamber volume 406 . Likewise, the sense layer 604 of the second micro sensor 214 may be exposed to the surrounding environment when the sense layer 604 of the first micro sensor 212 is masked by the mask layer 606 .

[0081] To achieve a selectively exposable sensor structure, each micro sensor may include one or more stacked and alternating columns of materials. For example, the first micro sensor 212 may have an initial configuration that includes an exposed sensing layer 608 deposited over the first mask layer 610 . Similarly, a first mask layer 610 may be stacked over the first sensing layer 612 . When the first sensor layer 612 is protected by the first mask layer 610 , the exposed sensing layer 608 may be open to the surrounding environment, eg, a chamber volume, to sense and monitor the wafer fabrication process. .

The second micro sensor 214 may include a structure similar to that of the first micro sensor 212 . For example, the second micro sensor 214 can have a second mask layer 614 over the second sensing layer 616 . However, in the initial configuration, the second mask layer 614 is applied to the surrounding environment such that the exposed sense layer 608 of the first micro sensor 212 protects the second sense layer 616 from the wafer fabrication process being monitored. can be opened to As described below, when the first sensing layer 612 has reached the end of its life, the second mask layer 614 may be removed to expose the second sensing layer 616 . Accordingly, the sensing capability of the wafer processing equipment may be refreshed and extended, and the second sensing layer 616 may be exposed to monitor the surrounding environment during a subsequent series of wafer processing cycles.

In one embodiment, alternating mask layers 606 of the first micro sensor 212 or the second micro sensor 214 may include different materials. More specifically, the materials forming the mask layers 606 may be susceptible to etching by different actions. As an example, a first mask layer 610 disposed below the sensing layer 608 exposed in the initial construction may be formed of a first mask material, and a second mask layer 610 that may be exposed to the surrounding environment during initial construction. 614 may be formed of a second mask material. The first mask material may be sensitive to etching by the etchant in the chamber volume, and the second mask material may not be sensitive to etching by the same etchant, or vice versa. Thus, when the second mask layer 614 is etched to expose the underlying second sense layer 616, the etchant used cannot remove the first mask layer 610, and thus the first micro sensor ( The underlying first sense layer 612 of 212 may remain intact and protected while the second sense layer 616 is monitoring the wafer fabrication process.

The sensing layers 604 in each micro sensor may be separated from each other by one or more mask layers 606 . For example, the exposed sensing layer 608 of the first micro sensor 212 may be separated from the first sensing layer 612 by a first mask layer 610 . That is, the first mask layer of the mask layer 606 may be between the exposed sense layer 608 and the first sense layer 612 . Similarly, an intermediate mask layer 618 may be disposed between the exposed sense layer 608 and the first sense layer 612 . For example, the intermediate mask layer 618 may be under the first mask layer 610 or over the first mask layer 610 as shown. In other words, the two sensing layers of the micro sensor may be separated by two or more mask layers of the micro sensor. Also, the mask layers of the same micro-sensor may include dissimilar materials. For example, the intermediate mask layer 618 may be formed of a different material that is susceptible to etching by a different etchant than the first mask layer 610 . Thus, the mask layers 606 of each micro sensor can be formed of dissimilar materials, which can be selectively etched by predetermined etchants to expose the underlying structure as desired.

The stacked structure shown in FIG. 6 may include sensing layers 604 representing individual micro-sensors or portions of micro-sensors. More specifically, the first microsensor 212 includes several stacked vertically offset capacitive microsensors having respective first and second conductors (such conductors are described below with respect to FIG. 9 ). can do. Alternatively, the first micro-sensor 212 may be considered to be a separate capacitive micro-sensor such that the elongate conductors of the capacitive micro-sensor as described below are insulated from each other by intervening mask layers 606 . It can be formed to have a stacked structure including several vertically separated sensing layers 604 that are

[0086] When the micro sensor includes a layered structure, etching of the various layers may change the parameters of the micro sensor. For example, if the sensor itself is layered, removal of the layers may change the capacitance of the sensor. Thus, as the capacitance changes, the sensor can be recalibrated to adjust the etch. That is, the sensor can be recalibrated to adjust the new base capacitance for accurate sensing of the wafer fabrication process.

Referring to FIG. 7 , there is shown a cross-sectional view of several micro sensors having a blanket mask layer 702 over selectively exposable sensing layers 604 , according to one embodiment. Several micro-sensors may be arranged side-by-side on the mounting surface 602 . The leftmost micro sensor may include an exposed sensing layer 608 in its initial configuration. In contrast, other micro-sensors, such as first micro-sensor 212 and second micro-sensor 214 , may include sensing layers 604 and mask layers 606 , respectively. For example, the first micro sensor 212 may include a first mask layer 610 on the first sensing layer 612 . Similarly, the second micro sensor 214 can include a second mask layer 614 over the second sensing layer 616 .

As shown, each of the mask layers 606 of each micro sensor may be part of a blanket mask layer 702 . More specifically, a continuous mask coating may be applied over each of the sensor probes to protect the overlying sensing layers 604 when the exposed sensing layer 608 is monitoring the surrounding environment during initial configuration. can The blanket mask layer 702 may be resistant to etchants used while the wafer fabrication process is monitored by the exposed sense layer 608 . As described below, when the exposed sense layer 608 has reached end-of-life, another etchant to which the blanket mask layer 702 is sensitive may be used, which will reduce the thickness of the blanket mask layer 702 , as will be described below. The mask material may be removed to expose adjacent microsensors, eg, first microsensors 212 .

[0089] The blanket mask layer 702 has a variable thickness such that the underlying micro sensors 210 are sequentially exposed by the etchant based on the respective thickness of the portion of the blanket mask layer 702 covering the micro sensor. It may include a layer profile. For example, the blanket mask layer 702 may include a first mask layer 610 over the first sense layer 612 having a first thickness, and a second mask layer 614 over the second sense layer 616 It may have a wedge-shaped layer profile as shown to have a second thickness different from this first thickness. That is, the first thickness may be less than the second thickness, so that removing the blanket mask layer 702 at a uniform rate will expose the first sensing layer 612 before the second sensing layer 616 . will be. The layer profile of the blanket mask layer 702 may include a profile of any variable thickness. For example, the layer profile may be stepped, parabolic, or the like.

Referring to FIG. 8 , there is shown a cross-sectional view of several micro sensors having mask layers 606 of different materials over selectively exposable sensing layers 604 , according to one embodiment. Several sets of micro sensors may be arranged on the mounting surface 602 . Each set of micro sensors may include respective sensing layers 604 covered by respective mask layers 606 . For example, the set of first micro sensors 212 may include respective first mask layers 610 over respective first sensing layers 612 (hidden). Similarly, the second set of micro sensors 214 may include respective second mask layers 614 over each of the second sense layers 616 (hidden). At any point during the wafer fabrication process, the set of micro sensors may include respective exposed sensing layers 608 . Thus, the exposed sense layers 608 can monitor the wafer fabrication process while the sense layers 604 of other sets of micro sensors remain protected under the respective mask layers 606 , e.g. For example, it may be etched.

[0091] Each of the mask layers 606 of the various sets of micro sensors may be formed of different materials susceptible to etching by different etchants. Accordingly, the various sets of mask layers 606 are selectively removed to expose the underlying sense layers 604 when another set of exposed sense layers 608 has been used and/or has reached end-of-life. can be

In one embodiment, each set of micro sensors is electrically connected to a respective electrical bus 802 . Thus, sets of microsensors may be individually sampled to detect changes in the parameters of the microsensors, thereby measuring and monitoring the wafer fabrication process.

[0093] The sensor schemes described above may be combined into a hybrid sensor configuration. For example, multilayer sensor structures as described with respect to FIG. 6 may include a top mask having a variable thickness, such as the profile shown in blanket mask layer 702 of FIG. 7 . The sensing layers 604 of a first set of micro sensors may be sequentially exposed by etching a variable thickness top mask, followed by subsequent sensing layers 604 of the micro sensors being stacked with vertically offset sensing layers 604 in a stack. ) by removing the intermediate mask layers 618 between them.

[0094] Referring to FIG. 9, there is shown a perspective view of a micro sensor of a wafer processing system according to one embodiment. The micro sensor 210 may include a capacitive micro sensor having a capacitance, wherein the capacitance of the micro sensor 210 may change in response to a wafer fabrication process performed by the wafer processing tool 102 . The micro sensor 210 may use two or more electrodes connected to a measurement circuit. For example, the micro sensor 210 may have a pair of conductors in a sensing layer, including a first conductor 902 separated from a second conductor 904 by a dielectric gap. The first conductor 902 and/or the second conductor 904 may be electrically charged. For example, one or more of the electrodes may be directly tied to drive and sense signals from the measurement circuitry of the electronic circuitry 218 . In one embodiment, one of the electrodes is connected to ground potential.

[0095] The first conductor 902 and the second conductor 904 may be formed of a conductive material, such as polysilicon, aluminum, tungsten, or the like. The conductors may be formed on the substrate 906 or otherwise mounted. The substrate 906 may be part of a wafer substrate 202 of the particle monitoring device 200 . Alternatively, the substrate 906 may be mounted on the wafer processing tool 102 . The substrate 906 may be a silicon wafer substrate, an organic material, a blanket glass substrate, or other solid dielectric substrate, such as alumina, quartz, silica, or the like.

Each conductor may include several fingerlike conductors extending from the conductive pad 908 along respective planes. For example, the first conductor 902 may include several first elongate conductors 910 , and the second elongate conductor 912 may include several second elongate conductors 912 . can do. In one embodiment, the first elongate conductors 910 and the second elongate conductors 912 are interdigitated. More particularly, the elongate conductors may be interlocked or interdigitated in the same plane to form a capacitance between the finger-like structures. Signals may be carried into and out of the elongate conductors via conductive pads 908 . Accordingly, the micro sensor 210 may include a capacitor having a planar configuration.

[0097] The micro sensor 210 may be designed to maximize sensitivity. For example, the electrodes of the micro sensor 210 may be formed in a small size and separated by a small space. This size scaling can achieve high sensitivity and active area density by making the sensors individually and collectively sensitive to smaller particles and more discretely detectable. As an example, each elongate conductor may be separated by a dielectric gap distance of less than 3 microns. In some embodiments, the dielectric gap distance may range from 50 to 100 nm. Thus, the micro sensor 210 can detect small perturbations in the dielectric properties between the electrodes. The design of the monitoring and control electronics 218 may also be manipulated to modulate the sensitivity. Accordingly, typical detection ranges of the micro sensors 210 may be in the range of low femtofarads to tens of picofarads, and the detection resolution may be on the order of attofarads.

Referring to FIG. 10 , there is shown a perspective view of a micro sensor of a wafer processing system according to one embodiment. The micro sensor 210 may include a coating 1002 over one or more of the first conductor 902 or the second conductor 904 . For example, coating 1002 may be applied over areas of patterned conductors with planar interdigitated capacitors. Coating 1002 may be an organic or dielectric material. More specifically, the coating 1002 may include a material selected to be responsive to the wafer fabrication process. For example, the coating 1002 may include a target material of an etching process. In one embodiment, coating 1002 includes a dielectric material such as silicon oxide or silicon nitride. Accordingly, when the etching process is performed by the wafer processing tool 102 , an amount of the coating 1002 may be removed.

In one embodiment, the coating 1002 forms part of the mask layer of the micro sensor 210 , and the conductors 902 , 904 form part of the sensing layer of the micro sensor 210 . The sensor layers are also multi-layered and may include intervening mask layers as described above.

Referring to FIG. 11 , there is shown a cross-sectional view taken along line A-A of FIG. 10 of a micro sensor of a wafer processing system according to one embodiment. The micro sensor 210 includes a pair of conductors 1102 over a substrate 906 . The pair of conductors 1102 may include, for example, a first elongate conductor 910 of a first conductor 902 and a second elongate conductor 912 of a second conductor 904 . As noted above, the pair of conductors 1102 may be at least partially covered by the coating 1002 . The coating 1002 may be a blanket coating as shown in FIG. 10 . More specifically, the coating 1002 includes a filler portion 1104 that laterally fills the dielectric gap between the interdigitated conductors, and an overcoat portion layered over the top surfaces of the conductors. (1106) may be included. Coating 1002 may have a layered structure, for example filler 1104 may be a first layer formed of a first material such as a hard dielectric, such as an oxide or nitride, and overcoat 1106 may be formed of a first material such as an organic material. It may be a second layer formed of two materials. It will be appreciated that any portion of the coating 1002 is optional. For example, in one embodiment, the coating 1002 includes filler 1104 laterally between the conductors, and the coating 1002 does not include an overcoat 1106 such that the top surfaces of the conductors are exposed. Alternatively, the coating 1002 may include an overcoat 1106 over the conductors, wherein the coating 1002 includes a filler 1104 such that voids exist in the dielectric gap laterally between the conductors. may not Other embodiments of coating 1002 may be used. For example, the coating 1002 may be conformal such that, for example, a thin conformal coating 2 nanometers thick is layered over the top and lateral surfaces of the substrate 906 and conductors. do. The elongated conductors may have a thickness or a height or width of greater than 3 microns, for example, of the conformal coating 1002 , such that the coating 1002 may cover the entire surface of the micro sensor 210 , and a pair of At least a portion of the dielectric gap between the conductors 1102 of

Deposition of material 1108 on any portion of micro sensor 210 may result in a change in capacitance of micro sensor 210 . For example, deposition of material 1108 onto the interdigitated finger-like structures shown in FIG. 9 or coating 1002 shown in FIG. can change

In one embodiment, the material 1108 deposited on the micro sensor 210 is a gas. Accordingly, the micro sensor 210 may include several surface area increasing structures. For example, the surface area increasing structures may include fibers or pores 1110 designed to trap or absorb gas. For example, the coating 1002 may include a material having a predetermined porosity to absorb a gas such as a sponge within the process chamber 114 , for example, a porous oxynitride. When the gas is absorbed by the pores 1110 , the gas increases the dielectric constant of the bulk material compared to the air-filled pores 1110 , for example, thereby causing the dielectric of the coating 1002 . You can change the constant, and the capacitance can change.

Removal of material from the micro sensor 210 may result in a change in the capacitance of the micro sensor 210 . For example, removal of material 1108 from interdigitated finger-like structures or coating 1002 may change the capacitance by changing the electric field.

A change in capacitance caused by deposition or removal of material 1108 may be sensed to determine an amount or rate of deposition. For example, the change in capacitance can be directly correlated with the amount of material 1108 added or removed. Also, if the capacitance can be monitored in real time, the etch rate in angstroms per minute, for example, can be calculated. Preliminary data indicates that capacitance changes of the micro sensors 210 can be measured to detect the presence of particles on the micro sensors 210 . Additionally, several micro sensors 210 can be multiplexed to detect relatively large particles. Similarly, a combination of micro sensors 210 may be used to determine particle size.

Material selection of conductors 902 , 904 , substrate 906 , and coating 1002 may be made based on a process used by micro sensor 210 to monitor or control. For example, one or more of the structures may be impermeable to the etch process being monitored. For example, the coating 1002 may be designed to be removed by an etching process, and the substrate 906 may be designed to be impermeable to the etching process. Similarly, coating 1002 may be process removable, and the elongate conductors may not be process removable.

The geometry of the structures of the micro sensor 210 may also be designed to correspond to a monitored or controlled process. For example, if the process includes material deposition, the finger-like structures are placed as close to each other as possible to ensure that a detectable change in capacitance occurs when material 1108 is deposited on or between conductors. can be The thickness of the conductors can also be varied. For example, the interdigitated elongate conductors are not planar, but rather thickened to make the structure more like a parallel plate structure.

12 , there is shown a schematic diagram of a micro sensor of the transistor sensor type of a wafer processing system, according to one embodiment. In one embodiment, the one or more micro sensors 210 of the wafer processing equipment include a transistor sensor 1200 . Transistor sensor 1200 may form part of a sensing layer of micro sensor 210 . Transistor sensor 1200 may include one or more transistors, eg, MOSFET 1202 . The MOSFET 1202 may include a source 1204 , a drain 1206 , and a gate 1208 . Transistor sensor 1200 may also include a collector 1210 that receives or discharges material 1108 during the wafer fabrication process. The collector 1210 may be physically isolated from the MOSFET 1202 , but the subcomponents may be electrically connected to each other. For example, collector 1210 may be electrically coupled to gate 1208 of MOSFET 1202 via electrical trace 1212 . Thus, MOSFET 1202 detects that material 1108 has settled on or evaporated from collector 1210 even when collector 1210 is positioned at a predetermined location away from MOSFET 1202 . can be configured to

Collector 1210 may be sized and configured to receive material 1108 . For example, a typical size of particles 1108 of material may range from 45 nanometers to 1 micron, such that collector 1210 includes an outer profile having an outer rim having a diameter of at least 1 micron. can do. The shape of the outer rim when viewed from the downward direction may be circular, rectangular or any other shape. Also, collector 1210 may be flat, ie, have a planar sensor surface, or collector 1210 may have a conical sensor surface. In one embodiment, collector 1210 is not a separate structure from MOSFET 1202 , but instead is incorporated into MOSFET 1202 . For example, collector 1210 may be a collection region on gate 1208 of MOSFET 1202 .

Similar to the micro-resonator sensor 1300 described below, the collector 1210 of the transistor sensor 1200 may include a sensor surface configured to simulate a surface of a wafer 402 . For example, the transistor sensor 1200 may be positioned near the wafer 402 , such as on a holding surface 412 , the sensor surface being oriented to face a forward direction parallel to the direction the wafer surface is facing. can Collector 1210 may include a multi-layered structure having, for example, a base layer and a top layer of the same or different materials.

In one embodiment, the parameter of the transistor sensor 1200 corresponds to the MOSFET 1202 . More specifically, the parameter of transistor sensor 1200 may be the threshold voltage of MOSFET 1202 measured across gate 1208 . The threshold voltage may directly correspond to the presence or absence of material 1108 on collector 1210 . For example, the threshold voltage may have a first value when a first amount of material 1108 is on collector 1210 , and the threshold voltage is such that a second amount of material 1108 is on collector 1210 . may have a second value (different from the first value) when present. Accordingly, the material 1108 collected or emitted from the sensor surface of the collector 1210 may be determined based on the threshold voltage of the transistor sensor 1200 . The processor 508 may be configured to detect a change in threshold voltage, so that when a change in the threshold voltage is detected, the wafer processing tool 102 detects the change in particle detection, or deposition of material 1108 , or It can be recorded as the amount of removal. The threshold voltage may be recorded over time to determine an actual deposition rate of material 1108 on wafer 402 or an actual removal rate of material 1108 from wafer 402 .

[00111] Referring to FIG. 13, there is shown a schematic diagram of a micro-resonator type micro sensor of a wafer processing system, according to one embodiment. In one embodiment, the one or more micro sensors of the wafer processing tool 102 include a micro-resonator sensor 1300 . The micro-resonator sensor 1300 may form part of the sensing layer of the micro sensor 210 . The micro-resonator sensor 1300 is a suitable resonant mass sensor such as a quartz crystal microbalance (QCM), a Surface Acoustic Wave (SAW), or Film Bulk Acoustic Resonators (FBAR). ), all of which quantify the cumulative mass 1302 of airborne particles deposited on their surfaces. A description of the complexity and variety of micro-resonator sensors 1300 is not described herein for the sake of brevity and ease of understanding, for purposes of brevity and ease of understanding. The micro-resonator sensor(s) 1300 may be distributed at predetermined locations on the particle monitoring device 200 or the wafer processing tool 102 . Each micro-resonator sensor 1300 may have a characteristic frequency, eg, a resonant frequency, as is known in the art. For example, without going into great detail, the micro-resonator sensor 1300 may be represented as a simple mass-spring system. The characteristic frequency of the micro-resonator sensor 1300 may be inversely proportional to the mass 1302 of the micro-resonator system. For example, the characteristic frequency may be proportional to the sqrt(k/M) of the micro-resonator sensor 1300, where 'M' corresponds to the mass 1302 and 'k' is the micro-resonator sensor ( 1300) corresponding to the proportionality constant. Accordingly, it will be appreciated that the characteristic frequency shifts when the micro-resonator sensor 1300 receives or releases the material 1108 during, for example, a wafer fabrication process. For example, when a material 1108 , such as a semiconductor material, is deposited on or removed from the sensor surface of the micro-resonator sensor 1300 within the process chamber 114 of the wafer processing tool 102 , the micro The mass 1302 of the resonant sensor 1300 changes, and thus the characteristic frequency shifts.

In one embodiment, the sensor surface includes material 1108 . More specifically, the sensor surface may be formed of the same semiconductor material 1108 as the material 1108 deposited on or removed from the wafer 402 during the wafer fabrication process. For example, if the wafer fabrication process is a deposition process for depositing silicon on a silicon wafer 402 , the sensor surface may include silicon and deposited material 1108 in a manner similar to interaction with the wafer 402 . to interact with the sensor surface. Similarly, if the wafer fabrication process is an etch process to remove silicon from a silicon wafer 402 , the sensor surface may contain silicon and material 1108 at a rate similar to the removal rate of silicon from the silicon wafer 402 . is etched from the sensor surface. Thus, the sensor surface may simulate the surface of the wafer 402 to measure the actual deposition rate or removal rate concurrently occurring on the wafer 402 during the wafer fabrication process.

[00113] Referring to FIG. 14, there is shown a schematic diagram of a micro sensor of the optical sensor type of a wafer processing system according to one embodiment. In one embodiment, the one or more micro sensors of the wafer processing tool 102 include an optical sensor 1400 . The optical sensor 1400 may form part of the sensing layer of the micro sensor 210 . The optical sensor 1400 may be Micro-Opto-electro-Mechanical Systems (MOEMS) as known in the art, and may be formed directly on a substrate using known semiconductor processing operations. Descriptions of the complexity and diversity of MOEMS are not described herein for the sake of brevity and ease of understanding, for purposes of simplicity. The optical sensor 1400 may include several micro mirrors or lenses distributed over a sensor surface (not shown) of a substrate. Without going into great detail, the optical sensor 1400 may include an optical path 1402 emanating from the light source 1404 . The optical path 1402 may be between the light source 1404 and the light detector 1406 . In one embodiment, the parameter of the light sensor 1400 corresponds to whether light from the light source 1404 is received at the light detector 1406 . For example, the parameter may change in response to the material 1108 interfering with the optical path 1402 . That is, as particles of material 1108 pass or lie within optical path 1402 and block light between light source 1404 and light detector 1406 , the parameter may change. In one embodiment, as the particle passes through the light sensor 1400 , light from the light source 1404 is reflected along different optical paths 1402 towards another light detector 1406 . Detection of reflected light by another light detector 1406 may result in a change to a parameter of the light sensor 1400 . The parameter may be, for example, an output voltage of the light sensor 1400 corresponding to light detection. The processor 508 may be configured to detect a change in output voltage, such that when a change in the output voltage is detected and/or when a disturbance in the optical path 1402 is detected, the wafer processing tool 102 is configured to: This change can be recorded as the deposition of material 1108 on the sensor surface on the substrate or removal of material 1108 from the sensor surface, so that the amounts and/or rates of deposition/removal are measured and can be monitored.

[00114] Since the micro-sensor types described above operate based on electrical parameters independent of external pressures, they may include one or more of a micro-resonator sensor 1300 , a transistor sensor 1200 , or a light sensor 1400 . It will be appreciated that the particle monitoring device 200 or wafer processing tool 102 having one or more micro sensors 210 may operate in any pressure regime, including under vacuum conditions. Similarly, microsensors can operate regardless of the gas consistency of chamber volume 406 , including under plasma-free conditions.

The particle monitoring device 200 or wafer processing tool 102 may include any combination of the sensors described above. For example, the micro sensors 210 may be grouped by thousands on the lower substrate. More specifically, the micro-sensors 210 may be connected in banks, such that a basic capacitance may be selected by selecting a different number of capacitors from the banks. Such selection may be controlled by the processor 508 . In one embodiment, the processor 508 monitors different types of sensors. For example, a micro-sensor 210 configured to detect material deposition and a micro-sensor 210 configured to detect material etch are monitored simultaneously, or monitored during different stages of a wafer fabrication process, to collect additional data and to be a multi-purpose sensor can form. Similarly, analog-to-digital capacitive measurement circuitry can be used to monitor the micro sensors 210 at different frequencies to obtain additional information. For example, the measurement circuitry may search the one or more micro sensors 210 by sweeping at a low or high frequency, or through a wide range of frequencies, to gather additional information.

For example, a wafer processing tool 102 having micro sensors mounted on the process chamber 114 may be used to monitor or control a wafer fabrication process. Monitoring includes refreshing or exposing the sensing layers of the micro sensors as the active micro sensors reach end-of-life. Although not limiting, several methods of performing such monitoring and control are described below. For brevity, the operations in the methods described below may refer to monitoring of a micro sensor having a capacitance parameter, although the methods may be adapted to include other micro sensor types, such as the micro sensor types described above.

[00117] Referring to FIG. 15, there is shown a diagram of a flow diagram representing operations of a method of refreshing micro sensors of a wafer processing equipment, according to one embodiment. 16A-16C show operations of the method described in FIG. 15 , whereby FIGS. 15 and 16A-16C are described together below.

[00118] The wafer processing equipment may include selectively exposable micro-sensors as described above with respect to FIG. 7 . At operation 1502 , a wafer fabrication process may be initiated in process chamber 114 . Referring to FIG. 16A , a wafer 402 may be loaded into a chamber volume with several micro sensors 210 and the etching process may be initiated. As shown in FIG. 16A , the leftmost micro sensor 210 may be exposed in the initial configuration. That is, when the wafer fabrication process begins, the leftmost micro sensor 210 may be exposed to the chamber volume 406 .

At operation 1504 , the wafer fabrication process may include etching to remove material from the wafer 402 . The leftmost micro sensor 210 may be an exposed micro sensor having a sensing layer comprising a wafer-like material. Thus, the exposed sensor surface on the exposed sensing layer of the exposed micro-sensor may be etched by an etchant in the wafer fabrication process. Thus, the exposed micro-sensor can detect and monitor material removal during the wafer fabrication process.

The first micro sensor 212 , which may be adjacent the exposed micro sensor, may include a first mask layer 610 exposed in the chamber volume 406 . The first mask layer 610 may be impermeable to the etchant used during the wafer fabrication process. Accordingly, the first sensing layer 612 under the first mask layer 610 may be protected from etching processes during steps of the wafer fabrication process.

[00121] The exposed micro-sensor may be etched until the sensor reaches end-of-life. The exposed micro-sensor may be monitored to determine when the surface morphology of the exposed sensing surface has changed in such a way that the sensitivity of the sensor is outside an acceptable range, indicating end-of-life. Testing exposed microsensors for end-of-life may include electrical diagnostic procedures. For example, an electrical input may be passed to an exposed micro-sensor via a corresponding electrical trace 216 , and an output from the exposed micro-sensor may be measured. An output of the exposed micro-sensor may be in response to an input signal, and may correspond to a parameter of the micro-sensor. For example, the output may correspond to the sensitivity of the exposed micro-sensor. In such a case, the sensitivity may vary based on the surface morphology, so that when the output is a predetermined value, it may be determined that the exposed micro-sensor is in an end-of-life state. In one embodiment, the exposed micro sensor may be in an end-of-life state when a parameter of the micro sensor behaves in a predetermined manner. For example, if the exposed microsensor is a capacitive microsensor, the exposed microsensor may be in an end-of-life state when the capacitance of the microsensor no longer changes linearly with respect to the wafer fabrication process.

[00122] When an exposed micro-sensor needs to be disposed of for replacement, other micro-sensors may be selectively exposed. In operation 1506 , the first mask layer 610 of the first micro-sensor 212 shown adjacent the exposed micro-sensor is peeled off and the first on the first sensing layer 612 of the first micro-sensor 212 is removed. 1 The sensor surface can be exposed. Exfoliation of the first mask layer 610 may be performed using various techniques. For example, the mask layer may be peeled off by a chemical that attacks the first mask layer 610 . The chemical recipe may vary depending on the mask material. For example, the blanket mask layer 702 including the first mask layer 610 may include an oxide or nitride, and the exfoliation chemistry may be suitably formulated to remove the oxide or nitride material.

In one embodiment, the blanket mask layer 702 is formed of a different material than the wafer fabrication process is designed to remove. For example, a wafer fabrication process may be designed to remove oxide material, such that the blanket mask layer 702 may be formed of a protective nitride layer. Accordingly, the target material of the wafer fabrication process may be impermeable to the etchant used to exfoliate the first mask layer 610 .

[00124] The mask layer covering the sensor surface may be peeled off using alternative techniques. For example, the mask layer may be peeled off using a thermal technique that causes the mask layer to decompose and/or dissolve, ie, an elevated temperature. In one embodiment, the mask layer may be degraded and/or dissolved using other agents. For example, water may be applied to the mask layer 702 to dissolve and exfoliate the mask layer 702 such that the underlying sensing layer is exposed.

As shown in FIG. 16B , the blanket mask layer 702 may be peeled off to expose the first micro sensor 212 to the right of the disposed leftmost micro sensor 210 . In one embodiment, the leftmost micro sensor 210 may be removed from service by stopping any electrical sampling of the sensor, ie by electrically disconnecting the sensor. The removal rate of the blanket mask layer 702 may vary for different reasons, such as with variations in the etching process, so that the blanket mask layer 702 exposes the first micro sensor 212 . Detecting when sufficiently stripped, but not sufficiently stripped to expose the second sensing layer 616 of the second microsensor 214 can provide useful information. For this purpose, the first micro-sensor 212 and the second micro-sensor 214 can be monitored simultaneously during exfoliation of the mask layer. For example, a parameter of the micro-sensors, eg capacitance, can be sensed. The capacitance may vary based on the thickness and/or presence of the mask layer over the sense layer of the micro sensors, such that when the mask layer is removed from the first sense layer 612 and still exists over the second sense layer 616 . can be decided. Such diagnostics can be used to trigger the next action in the wafer fabrication process, for example, the continuation of the wafer etching process.

In an operation 1508 , the exposed sensor surface on the exposed first sense layer 612 may be etched during a wafer fabrication process. That is, the wafer fabrication process may include etching the wafer, and the first micro sensor 212 may be activated to sense the process. This may continue until the first microsensor 212 reaches an end of life, which may be determined as described above.

In operation 1510 , the second mask layer 614 of the second micro sensor 214 may be peeled off to expose a second sensor surface on the second sensing layer 616 . Selective exposure of the second sensor surface may be performed using any of the exfoliation techniques described above. Thus, the second micro sensor 214 protected during a previous segment of the wafer fabrication process may be exposed to become an active sensor during a subsequent segment of the wafer fabrication process. The first micro sensor 212, which may be in an end-of-life state, may be disposed of during a subsequent segment.

In an operation 1512 , the exposed sensor surface on the exposed second sense layer 616 may be etched during a wafer fabrication process. That is, the wafer fabrication process may include etching the wafer, and the second micro sensor 214 may be activated to sense the process. This may continue until the second micro sensor 214 has reached an end of life, which may be determined as described above. The procedure described above can be repeated to expose additional micro sensors to continuously sense the wafer fabrication process for an extended period of time, eg, hundreds of process cycles.

Referring to FIG. 17 , there is shown a diagram of a flowchart illustrating operations of a method of refreshing micro sensors of wafer processing equipment, according to one embodiment. 18A-18F show the operations of the method described in FIG. 17 , so FIGS. 17 and 18A-18F are described together below.

[00130] The wafer processing equipment may include several selectively exposable micro-sensors as described above with respect to FIG. 6 . At operation 1702 , a wafer fabrication process may be initiated in a process chamber. Referring to FIG. 18A , the first micro sensor 212 may include an exposed sensing layer in an initial configuration. In an initial configuration, the second micro sensor 214 may include a second mask layer 614 that protects the underlying second sensing layer 616 . More specifically, the second sense layer 616 may be protected by the second mask layer 614 while a wafer in the process chamber is being processed.

At operation 1704 , the wafer fabrication process may include etching to remove material from the wafer. The exposed sensing layer of the first micro sensor 212 may include a wafer-like material. Accordingly, the exposed sensor surface on the exposed sensing layer may be etched by an etchant in the wafer fabrication process. Accordingly, the exposed sensing layer of the first micro sensor 212 can sense and monitor material removal. However, the etchant used to remove material from the first sensor surface may not remove material from the second mask layer 614 . That is, the second micro sensor 214 , which may be adjacent to the first micro sensor 212 , may include a second mask layer 614 exposed to the chamber volume. The second mask layer 614 may be formed of a different material than the exposed sensing layer, so that the second sensing layer 616 under the second mask layer 614 is protected from etching processes during steps of the wafer fabrication process. can be

The exposed sensing layer of the first micro sensor 212 may be etched until the sensor reaches end-of-life. When the first micro-sensor 212 needs to be refreshed, the second sensing layer 616 of the second micro-sensor 214 may be selectively exposed.

Referring to FIG. 18C , in operation 1706 , any remaining sensor material of the first sensing layer 612 may be peeled off before or after exposing the second sensing layer 616 . For example, any of the exfoliation techniques described above may be used to remove the remaining first sensing layer 612 .

In operation 1708 , the second sense layer 616 may be exposed by peeling off the second mask layer 614 . Any of the exfoliation techniques described above may be used to remove the second mask layer 614 . The second mask layer 614 may be impermeable to the etchant used to process the wafer, and the second mask layer 614 may be susceptible to etching by other etchants that do not attack the wafer. Accordingly, the second mask layer 614 may be peeled off after removal of the exposed sense layer 608 without affecting the wafer or the first mask layer 610 exposed to the chamber volume. More specifically, the second mask layer 614 may be formed of a different material than the first mask layer 610 , such that application of an etchant may remove one mask layer but remove another mask layer. Can not.

Referring to FIG. 18D , in operation 1710 , after removing the second mask layer 614 to expose the second sensing layer 616 , the first mask layer ( 610 may be stripped to expose intermediate mask layer 618 . An intermediate mask layer 618 may be formed over the lower sensing layer 604 of the first micro sensor 212 . More specifically, the intermediate mask layer 618 may be formed of a material that is impermeable to etching by the etchant used to process the wafer. For example, the intermediate mask layer 618 may have the same material as the second mask layer 614 that protects the second sense layer 616 during an initial stage of the wafer fabrication process. Thus, the intermediate mask layer 618 will not be attacked by the etchant when the second sense layer 616 is monitoring a process.

Referring to FIG. 18E , in operation 1712 , the exposed sensing layer of the second micro sensor 214 may be used to sense and monitor the wafer fabrication process. For example, the second sensing layer 616 may monitor material removal from the wafer. At the same time, the intermediate mask layer 618 may protect the lower sensing layer of the first micro sensor 212 . The exposed sensing layer of the second micro sensor 214 may be etched until the sensor reaches end-of-life.

Referring to FIG. 18F , when the second micro sensor 214 needs to be replaced, the first micro sensor 212 can be refreshed by exposing another sensing layer 604 . More specifically, the second sensing layer 616 and the intermediate mask layer 618 are peeled away from their respective microsensors to expose the lower sensing layer 604 of the first microsensor 212 and the second microsensors. The mask layer 606 of the sensor 214 may be exposed. Accordingly, the stacked structures of the first micro sensor 212 and the second micro sensor 214 may be sequentially etched to intermittently expose the sensing layers, which refreshes the sensing capability of the micro sensors and wafer manufacturing equipment.

19 , shown is a block diagram of an exemplary computer system of a wafer processing system in accordance with one embodiment. One or more components of the illustrated computer system 104 may be used in the electronic circuitry 218 of the wafer processing tool 102 . Accordingly, the electronic circuitry 218 discussed above with respect to FIG. 5 may be a subset of the computer system 104 . Alternatively, the electronic circuitry 218 may be local to the particle monitoring device 200 or the wafer processing tool 102 , and the computer system 104 may be local to the electronic circuitry 218 and/or the wafer processing tool 102 . It may be a manufacturing facility host computer that interfaces with the computer. In one embodiment, computer system 104 is coupled to and controls robots, loadlocks 112 , process chambers 114 and other components of wafer processing tool 102 . Computer system 104 may also receive and analyze particle detection or material deposition/removal information provided by micro sensors 210 as described above.

The computer system 104 may be connected (eg, networked) to other machines over a Local Area Network (LAN), an intranet, an extranet, or the Internet. Computer system 104 may operate as a server or client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. can work Computer system 104 may be a personal computer (PC), tablet PC, set-top box (STB), personal digital assistant (PDA), cellular telephone, web appliance, server, network router, switch or It can be a bridge, or any machine capable of executing (sequentially or otherwise) a set of instructions that specify actions to be taken by that machine. Also, although only a single machine is shown with respect to computer system 104 , the term “machine” also refers to individually a set (or multiple sets) of instructions for performing any one or more of the methods described herein. It should be taken to include any set of machines running as or together.

The computer system 104 may include a non-transitory machine-readable medium storing instructions that can be used to program the computer system 104 (or other electronic devices) to perform a process in accordance with embodiments. computer program product or software 1902 with Machine-readable media includes any mechanism for storing or transmitting information in a form readable by a machine (eg, a computer). For example, machine-readable (eg, computer-readable) media may include machine (eg, computer)-readable storage media (eg, read-only memory (“ROM”), random access memory (“” RAM"), magnetic disk storage media, optical storage media, flash memory devices, etc.), machine (eg computer) readable transmission medium (electrical, optical, acoustic or other form of propagated signals (eg, for example, infrared signals, digital signals, etc.)) and the like.

In one embodiment, the computer system 104 includes a system processor 1904 , main memory 1906 (eg, read-only memory (ROM), flash memory, dynamic random access memory (DRAM), such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), static memory 1908 (e.g., flash memory, static random access memory (SRAM), etc.), and secondary memory (e.g., data storage device 1924) ), and they communicate with each other via a bus 1909 .

The system processor 1904 represents one or more general-purpose processing devices, such as a microsystem processor, central processing unit, or the like. More specifically, system processor 1904 is a complex instruction set computing (CISC) microsystem processor, a reduced instruction set computing (RISC) microsystem processor, a very long instruction word (VLIW) microsystem processor, a system implementing other instruction sets. It may be a processor, or system processors implementing a combination of instruction sets. The system processor 1904 may also be one or more special-purpose processing devices, such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal system processor (DSP), a network system processor, or the like. The system processor 1904 is configured to execute processing logic 1910 for performing the operations described herein.

The computer system 104 may further include a system network interface device 1912 for communicating with other devices or machines, eg, the wafer processing tool 102 , via a network 1914 . Computer system 104 may also include a video display unit 1916 (eg, a liquid crystal display (LCD), light emitting diode display (LED), or cathode ray tube (CRT)), an alphanumeric input device 1918 ) (eg, a keyboard), a cursor control device 1920 (eg, a mouse), and a signal generating device 1922 (eg, a speaker).

[00144] The secondary memory may include a data storage device 1924 having a machine-accessible storage medium 1926 (or more specifically a computer-readable storage medium), the machine-accessible storage medium comprising: , one or more sets of instructions (eg, software 1902 ) implementing any one or more of the methods or functions described herein are stored. The software 1902 may also reside fully or at least partially within the system processor 1904 and/or within the main memory 1906 during its execution by the computer system 104 , the main memory 1906 and the system processor 1904 also constitutes machine-readable storage media. The software 1902 may further be transmitted or received over the network 1914 via the system network interface device 1912 .

Although machine-accessible storage medium 1926 is shown as being a single medium in an exemplary embodiment, the term “machine-readable storage medium” refers to a single medium or multiple media (eg, centralized or distributed databases and/or associated caches and servers). The term “machine-readable storage medium” also includes any medium capable of storing or encoding a set of instructions for execution by a machine and causing a machine to perform any one or more of the methods. will be taken as Accordingly, the term “machine-readable storage medium” shall be taken to include, but is not limited to, solid-state memories, and optical and magnetic media.

[00146] In the foregoing description, certain exemplary embodiments have been described. It will be apparent that various modifications may be made to the embodiments without departing from the scope of the following claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

Claims (15)

a process chamber having a chamber volume;
a first micro sensor mounted within the chamber volume, the first micro sensor comprising a first mask layer over a first sensing layer; and
a second micro sensor mounted within the chamber volume, the second micro sensor comprising a second mask layer over a second sensing layer;
The first micro sensor and the second micro sensor have respective parameters and include respective sensor surfaces on respective sensing layers, and the respective parameters are determined when material is removed from the respective sensor surfaces. changing,
Wafer processing tools. According to claim 1,
and an exposed sensing layer mounted within the chamber volume and open to the chamber volume;
Wafer processing tools. 3. The method of claim 2,
the first mask layer has a first thickness and the second mask layer has a second thickness different from the first thickness;
Wafer processing tools. 4. The method of claim 3,
wherein the first mask layer and the second mask layer are portions of a blanket mask layer having a layer profile comprising a variable thickness;
Wafer processing tools. 3. The method of claim 2,
the first mask layer has a first mask material, the second mask layer has a second mask material, the first mask material is susceptible to etching by an etchant in the chamber volume, and 2 the mask material is insensitive to etching by the etchant,
Wafer processing tools. 6. The method of claim 5,
wherein the first micro sensor comprises the exposed sensing layer, the first mask layer being between the exposed sensing layer and the first sensing layer;
Wafer processing tools. 7. The method of claim 6,
further comprising an intermediate mask layer between the exposed sense layer and the first sense layer;
Wafer processing tools. According to claim 1,
wherein the micro sensors include micro sensors, wherein the respective parameters are capacitances of the micro sensors, and the capacitances change when material is removed from the respective sensor surfaces;
Wafer processing tools. initiating a wafer fabrication process in a process chamber having a chamber volume, wherein a first micro sensor and a second micro sensor are disposed within the process chamber, a first sensing layer of the first micro sensor and a first sensing layer of the second micro sensor 2 mask layer exposed to the chamber volume;
etching a first sensor surface on a first sensing layer of the first micro sensor with an etchant; and
stripping a second mask layer of the second micro sensor to expose a second sensor surface on the second sensing layer of the second micro sensor to the chamber volume;
method. 10. The method of claim 9,
wherein the micro sensors include micro sensors having respective capacitances, wherein the respective capacitances change as material is removed from respective sensor surfaces;
method. 11. The method of claim 10,
measuring the respective capacitances; and
determining whether the second sensor surface on the second sensing layer has been exposed to the chamber volume based on the respective capacitances;
method. 11. The method of claim 10,
the etchant removes material from the first sensor surface and does not remove material from the second mask layer;
method. 10. The method of claim 9,
wherein the first micro sensor and the second micro sensor are mounted on a chamber wall within the chamber volume;
method. 10. The method of claim 9,
wherein the first micro sensor and the second micro sensor are mounted on a support surface of a particle monitoring device disposed within the chamber volume.
method. 10. The method of claim 9,
a third micro sensor disposed within the process chamber, a third mask layer of the third micro sensor exposed to the chamber volume, the third mask layer being thicker than the second mask layer;
method.

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